English Spanish Interpreter (ESI) is offered in two different bi-directional versions: ESI Standard and ESI Professional.
ESI Standard is a translator which gives you on-the-fly, context-sensitive translations of whole Microsoft Word documents or copy-pasted or typed-in texts.
ESI Professional additionally has Interactive functionality and Translation Memory, features which allow you to achieve even greater accuracies. You can add your own terminology as well.

Professional Version 4.46
The professional version not only has the context-sensitive, automatic, first-draft mode, but it also includes the following sophisticated features:
The unique Interactive Mode increases productivity, accuracy and style by allowing the user to select among grammatical and context-sensitive options. The user has full command over the translation process!
The Translation Memory, on the other hand, lets the user personalize the program by predefining translations and meanings for any word or phrase.
The Interpretation Mode offers a gisted back-translation in the source language for those who are not bilingual.
Users can also add the new words or meanings they need.

Features:

• Context-Sensitive
  
• Instead of translating literally, the ESI translates contextually using Artificial Intelligence, resulting in higher quality and precision.
• Interactive Mode
  Available in the Professional version only. Translate sentence by sentence, word by word and receive word and phrase options as you go. You have total control over the translation process and output.
• Translation Memory
  Available in the Professional version. Lets the user personalize the program by predefining translations and meanings for any word or phrase and it enables the program to remember the choices for future sessions.
• Huge Internal Dictionary
  600,000 translations, over 4 million synonyms and 1,300,000 conjugations included in ESI's database able to deal with any translation task. Also, with the add-on technical dictionaries, you can have 200,000 field-specific translations more.
• Huge Collection of Idioms/Phrasal Verbs
  Largest collection of phrasal verbs, locutions and idioms of all kinds available today allows ESI to render translations that comply not only with grammar and context, but with the idiomatic and cultural nuances of each language. About 225,000 idiomatic entries included.
• Other Tools in the Toolkit: Spell and Ambiguity Checkers
  Also included are Spell & Spanish Ambiguity Checkers, which help polish the source documents to avoid unwanted translations to come up.
• Supports Several Types of Files
  ESI supports MS-WordŽ .DOC files and .RTF files and includes Plug-ins for Microsoft Word and Excel.
• Text-to-Speech: Bilingual Pronunciation
  ESI pronounces words, phrases and complete documents, in both English and Spanish.
• Add-a-Word
  Increase your database by manually adding any new word you need. Perfect for those needing Corporation-Specific glossaries and terms. These newly-added words will migrate automatically to future new versions of the program.
• Fast Background Translation
  Available in the Professional version only. Perfect for large document translation. Multi-tasking allows you to continue working on something else while ESI translates the documents.
• Toolbar and Menu Activation within MS Office
  Available in the Professional version only. Just click on the buttons within your Microsoft Word or Microsoft Excel and the program will appear with translations, synonyms, conjugations and more!
• Extras
  Extra features: Letter, word and paragraph count. Time measuring for translation process, enhanced spell checker, printing, Spanish-character toolbar aid.